Communication system for vehicle, vehicle, and communication device for vehicle

ABSTRACT

The present invention is directed to vehicle communication equipment capable of transferring information using light without adding new light emitting means, and further, between a stationary apparatus and a vehicle or between vehicles. A light emitted from a signal lamp ( 11 ) of a stationarily installed traffic signal ( 10 ) or a head lamp ( 35 ) or a tail lamp ( 36 ) of a vehicle ( 20 ) is superimposed with a signal by a modulator ( 13 ), the modulated light is received by a light receiving unit ( 21 ) of the vehicle ( 20 ) side, and the received modulated light is demodulated by a decoder ( 22 ) to be displayed on a display panel ( 24 ).

TECHNICAL FIELD

The present invention relates to a vehicle communication system, avehicle, and vehicle communication equipment, and, in particular, itrelates to a vehicle communication system, a vehicle, and vehiclecommunication equipment that carry out information transfer by usinglight.

BACKGROUND ART

For example, in Japanese Patent Application Publication (KOKAI) No. Hei9-51309 there is proposed an inter-vehicle communication system,comprising: a forward light emitting/receiving unit for emitting orreceiving a laser beam signal to and from a forward direction of avehicle; a backward light emitting/receiving unit for emitting orreceiving a laser beam signal to and from a backward direction of thevehicle; and signal relay means for relaying signals between the forwardlight emitting/receiving unit and the backward light emitting/receivingunit so that a laser beam signal including a signal received by theforward light emitting/receiving unit is transmitted from the backwardlight emitting/receiving unit, and that a laser beam signal including asignal received by the backward light emitting/receiving unit istransmitted from the forward light emitting/receiving unit, therebyenabling a progressive transmission of signals to be established betweenvehicles, and thereby even in such cases where, for example, a pluralityof vehicles are lined up in queue in the forward direction due to atraffic congestion, where there is a too long inter-vehicle distance ina highway or the like, or where visibility between vehicles isdeteriorated due to rains, fog or the like, it is ensured for specificinformation owned by a specific vehicle to be transferred to othervehicles.

Further, in Japanese Patent Application Publication (KOKAI) No.2001-158390 there is disclosed inter-vehicle communication equipmenthaving a transceiver capable of exchanging information between vehiclesfor use in a saddle-mount type vehicle, on which an operator ride on asaddle thereof. The inter-vehicle communication equipment is installedadjacent to lighting means in order easily to secure its installationspace, in addition to facilitate adjustment of the position of thecommunication equipment, and thus to enable to improve receptionperformance thereof.

According to the inter vehicle communication system proposed by theJapanese Patent Application Publication (KOKAI) No. Hei 9-51309, becauseit transmits information between vehicles using a laser beam signal, itmust have light emitting/receiving units for emitting a laser beamspecific thereto provided at the front and the rear ends of the vehicle,thereby increasing the cost. Moreover, because this equipment carriesout information transmission using the laser beam, if the laser beamemitted from the aforementioned light emitting/receiving unit impingeson a human body, this part of the body may possibly be damaged, therebycausing a safety problem.

Further, according to the inter-vehicle communication equipmentdisclosed in the Japanese Patent Application Publication (KOKAI) No.2001-158390, because a separate transceiver must be installed adjacentto its lighting means, it requires a plurality of lighting meansadditionally, thereby complicating the equipment. And thus there is adisadvantage that the cost thereof increases.

The present invention is contemplated to solve the above-mentionedproblems associated with the conventional art, and an object thereof isto provide a novel vehicle communication system, a vehicle, and vehiclecommunication equipment which enables vehicle communication using thelight without requiring any new dedicated light emitting means.

DISCLOSURE OF THE INVENTION

The present invention is directed to a vehicle communication system,comprising:

a light emitting apparatus installed stationarily;

a modulator for modulating a light emitted from the aforementioned lightemitting apparatus by superimposing a predetermined signal thereon;

a light receiving apparatus installed on a vehicle side for receivingthe light emitted from the aforementioned light emitting apparatus andsuperimposed with the predetermined signal;

a decoder for reading out the signal superimposed on the light receivedby the aforementioned light receiving apparatus; and

notifying means for notifying information based on a signal which isread out by the aforementioned decoder.

Here, the aforementioned light emitting apparatus may be a signal lampof a traffic signal, a street lighting lamp, a warning lamp at arailroad crossing, an embed type signal lamp embedded in a vehicle laneor a signal lamp of a traffic signal installed along a railroad track.In particular, in a case of the signal lamp of the traffic signalinstalled along the railroad track, this signal lamp is to be receivedby a light receiving apparatus onboard a railway car. Further, theaforementioned modulator may be of a type operable to modulate bysuperimposing a coded pulse on a drive current of the aforementionedlight emitting apparatus.

Further, the present invention is directed to a vehicle, comprising:

a light emitting apparatus for emitting a light outwardly;

a modulator for superimposing a predetermined signal on the lightemitted from the aforementioned light emitting apparatus;

a light receiving apparatus for receiving a light which is emitted fromthe aforementioned light emitting apparatus of another vehicle and issuperimposed with a signal;

a decoder for reading out the signal superimposed on the light receivedby the aforementioned light receiving apparatus; and

output means for outputting a signal read out by the aforementioneddecoder.

Here, it should be noted that the aforementioned light emittingapparatus may be a head lamp, a tail lamp, a brake lamp, a turnindicator lamp or the like that are installed onboard a vehicle to castillumination lights or warning lights to external directions. Further,it may be such one capable of transmitting information between theaforementioned plurality of vehicles.

Further, it may be arranged such that the aforementioned decoder isprovided with identification means for identifying received signals andthat only a signal the ID code of which agreed is read out to beoutputted. Still further, it is preferably that the aforementioneddecoder has discrimination means for discriminating a type of thereceived signal so as to be able to carry out a signal processing independence on the type thereof. Preferably, the aforementioneddiscrimination means discriminates the type thereof by a category signalattached to the signal. Further, preferably, key operation means isprovided whereby, in response to a single operation of the key operationmeans, a different signal is superimposed on a respective light shedfrom a plurality of light emitting apparatuses installed onboard theaforementioned vehicle then the respective light is emitted from therespective light emitting apparatuses.

Still further, the present invention is directed to vehiclecommunication equipment, comprising:

a light emitting apparatus which is installed stationarily; and

a modulator for superimposing a predetermined signal on a light emittedfrom the light emitting apparatus, wherein

communication is carried out by emitting the light modulated by themodulator to an external vehicle.

Here, the aforementioned light emitting apparatus is preferablycomprised of LEDs. Further, the aforementioned light emitting apparatusis preferably a signal lamp of a traffic signal or a warning lamp at arailroad crossing.

Still furthermore, the present invention is directed to vehiclecommunication equipment comprising:

a light receiving apparatus for receiving a light which is superimposedwith a predetermined signal;

a decoder for reading out the signal superimposed on the light receivedby the aforementioned light receiving apparatus; and

notifying means for notifying information based on the signal read outby the aforementioned decoder. By way of example, the aforementionednotifying means here is preferably a display apparatus.

A preferred embodiment of the present invention relates to atransmission/reception system comprising: equipment capable oftransmitting and receiving signals between a station and a vehicle orbetween vehicles; a display unit functioning as a user interface; and anoperation unit, wherein signals are exchanged using a light emittingunit on a station side and/or of the vehicle. According to this system,a dialog is enabled by transmission of information between a stationaryapparatus installed relatively nearby and a vehicle or between vehicles.Further, because the exchange of signal is carried out by modulating alight emitted from the stationary apparatus or the vehicle and bysuperimposing a signal thereon, advantageously, original functions ofthe existing light emitting apparatuses of the stationary apparatus orthe vehicle are maintained as they are, and thus there is no need newlyto provide any additional light emitting apparatus.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front elevation showing a system configuration of vehiclecommunication equipment according to a first embodiment.

FIG. 2 is a block diagram showing a system configuration of thecommunication equipment.

FIG. 3 is a flowchart indicating operation of the communicationequipment.

FIG. 4 is a waveform diagram showing a pulse construction of informationto be transmitted.

FIG. 5 is a front elevation showing a system according to a modificationthereof.

FIG. 6 is a front elevation showing another system according to anothermodification.

FIG. 7 is a front elevation showing a system configuration according tostill another modification.

FIG. 8 is a front elevation showing a system configuration according tostill more another modification.

FIG. 9 is a front elevation showing a system according to a stillfurther another modification.

FIG. 10 is a front elevation showing an inter-vehicle communicationsystem according to a second embodiment of the invention.

FIG. 11 is a block diagram showing a system configuration of thecommunication equipment mounted in a vehicle.

FIG. 12 is a flowchart showing an operation at the time of signalreception.

FIG. 13 is a flowchart showing an operation at the time of signaltransmission.

FIG. 14 is a block diagram showing a receiving unit provided with adetection function.

FIG. 15 is a front elevation showing communication equipment accordingto a modification thereof.

FIG. 16 is a flowchart showing an operation of the equipment accordingto the modification.

BEST MODES FOR CARRYING OUT THE INVENTION (1) Embodiment 1 CommunicationEquipment for Use Between a Stationary Apparatus and a Vehicle: FIGS. 1to 8

A typical example of a first embodiment will be described by referringto FIGS. 1 to 4. This equipment is directed to vehicle communicationequipment for carrying out information transfer between a traffic signalstationarily installed and a vehicle. As shown in FIG. 1, a trafficsignal 10 installed at an intersection of roads or the like has a signallamp 11 including green, yellow and red colors. A light emitting unit ofthe signal lamp 11 is comprised, for example, of LEDs (Light EmittingDiodes). This signal lamp 11 is driven by a signal drive circuit 12which is conventionally known. And a modulator 13 is connected betweenthis drive circuit 12 and the signal lamp 11. The modulator 13 isfurther connected to a receiver 14. This receiver 14 receives a commandsignal from outside via an antenna 15.

Conversely, on the side of a vehicle 20, there are provided a lightreceiving unit 21, a decoder 22, a drive circuit 23, and a display panel24.

FIG. 2 shows a more specific configuration of the aforementionedcommunication system, in which a portion on the left hand side depicts asystem of the traffic signal 10. This system has a CPU 16, and this CPU16 is interposed between the receiver 14, the signal drive circuit 12and the modulator 13 for controlling them.

Further, a portion on the right hand side in FIG. 2 depicts a system onthe vehicle 20, in which a CPU 25 is connected to the decoder 22. And tothe CPU 25 there are connected an operation input unit 26, a memory 27and the drive circuit 23. The drive circuit 23 drives the display panel24.

In this arrangement described above, the receiver 14 on the side of thetraffic signal 10 receives a command signal by radio from a command unitvia the antenna 15. And the receiver 14 transfers this command signal tothe modulator 13. The modulator 13 superimposes the aforementionedcommand signal on a drive current for driving the signal lamp 11 to begenerated by the signal drive circuit 12. Thereby, the signal lamp 11sheds a light for signal display/lighting in a state superimposed withthe command signal.

The light which is superimposed with the aforementioned command signalis received by the light receiving unit 21 of the vehicle 20, and thesignal is demodulated by the decoder 22. Thereby, this signal thusdecoded is supplied to the drive circuit 23 to be displayed on thedisplay panel 24.

Here, information to be superimposed on the light shed from the signallamp 11 may be any information relating to a traffic regulation,no-right turn or one-way traffic information. Alternatively, theinformation may be the one indicating the time it takes for the trafficsignal to change to green indicating a go-sign or the like. Further,this information may be issued intermittently at a predetermined periodof time or when required.

FIG. 3 shows an example of operation of the vehicle communicationequipment. Here, the CPU 25 on the side of the vehicle 20 connected tothe decoder 22 therein discriminates whether or not a signal isreceived, and when the signal is received, loads a received data in aD-RAM of the CPU 25. And by carrying out check and compare operation ofIDs with the received data, and only in a case where IDs are agreedtherebetween, the received data is analyzed, and a search operationthrough a database stored in the memory 27 is carried out. Then, displaycontents to be given from the database are displayed on the displaypanel 24 operated by the drive circuit 23. Here, the ID check operationis carried out in order to omit the display of unnecessary informationor to cut the unnecessary information. However, this ID check operationmay be omitted if required so.

As a method of modulation for modulating the drive current of the signallamp 11 with the signal by means of the modulator 13, there mayappropriately be adopted various modulation methods such as AMmodulation, FM modulation, pulse width modulation, pulse code modulationor the like.

FIG. 4 shows an example of a signal construction based on the pulse codemodulation method, in which one frame is formed as a cyclic frame of 45ms period of time. Here, each frame is comprised of a guide pulse, adata code and a category code. A more specific exemplary construction ofthese pulses is shown in TABLE 1.

TABLE 1 Name Sign Pulse Width Deviation Guide Pulse Tg 2.4 ms ±0.1 msOff Time T OFF 0.6 ms ±0.1 ms On Time T ON “0” 0.6 ms ±0.1 ms T ON “1”1.2 ms ±0.1 ms Carrier fo 40.0 kHz ±400 Hz Frame Cycle Tf 45.0 ms ±0.1ms

As clearly known from the above TABLE 1, the guide pulse has a pulsewidth of 2.4 ms, in contrast to this, the data code, by sequentiallyforming a pulse of 0.6 ms pulse width indicating “0” and a pulse of 1.2ms pulse width indicating “1”, transfers a predetermined information. Itis to be noted, however, that this method of pulse forming by using themodulator 13 is only one example, and various other methods may beadopted depending on its object and the length of information.

Further, in a case of superimposing a signal on the light emitted fromthe signal lamp 11 on the basis of the pulse code modulation asdescribed above, it is preferable for the signal lamp 11 to be comprisedof LEDs which have excellent responsiveness. As for the types of thetraffic signal 10, it is applicable to versatile applications, namely,not only to the traffic signal for vehicles 10, but also to a pedestriansignal installed at a crossing.

Next, a modification of the aforementioned embodiment of the inventionwill be described by referring to FIG. 5. This embodiment of theinvention is directed to communication equipment for communicatingbetween a street lighting 30 installed along a road and a vehicle 20. Inthis case of the street lighting 30, also, a modulator 13 is connectedto its lamp drive circuit 12, and in addition, this modulator 13 isconnected to a receiver 14. And the receiver 14 has an antenna 15, andvia which receives a signal from a command station. By way of example,it is preferable for the street lighting 30 to use a LED, a xenon lamp,a discharge lamp, an HID or the like as its light source, wherebyresponsiveness with respect to the modulation by the modulator 13 willbe secured. Conversely, on the side of the vehicle 20, there areprovided a light receiving unit 21, a decoder 22, a drive circuit 23 anda display panel 24.

Thereby, it is arranged such that the street lighting 30 illuminates thelight which is superimposed with the signal by the modulator 13, thelight receiving unit 21 of the vehicle 20 receives this light then to beread out by the decoder 22 and displayed on the display panel 24 via thedrive circuit 23. Thereby, a predetermined display is given on thedisplay panel 24. By way of example, the display to be given thereon mayinclude an indication of the location at which the street lighting isinstalled, contents of traffic regulations such as one-way traffic andthe like, or any other related traffic information such as a state ofcongestion and the like. Further, as the street lighting for emittingthe light which is superimposed with the signal, any other types ofstreet lighting in addition to that indicated in FIG. 5 may beapplicable as well.

FIG. 6 shows still another embodiment of the invention. This relates tocommunication equipment for transmitting/receiving information between awarning lamp 31 installed at a railroad crossing and a vehicle 20. Thatis, the warning lamp 31 in this case is connected to a warning lampdrive circuit 12 and a modulator 13. On the other hand, on the side ofthe vehicle, there are provided a light receiving unit 21, a decoder 22,a drive circuit 23 and a display panel 24. A light emitting unit of thewarning lamp 31 is comprised of, for example, LEDs.

Thereby, it is arranged such that the warning lamp 31 emits a light onwhich a signal is superimposed by the modulator 13, this light isreceived by the light receiving unit 21 of the vehicle 20 side, and isdemodulated by the decoder 22 then to be displayed on the display panel24 by the drive circuit 23. Thereby, the signal which is superimposed onthe warning lamp 31 is enabled to be displayed on the display panel 24.

Contents of such display by the warning lamp 31 at the railroad crossingmay be, for example, the time it takes for this railroad crossing tobecome crossable or any other related information such as accident orthe like.

Further, it is also possible to install the warning lamp 31 in a liftinggate 33 at a railroad crossing as shown in FIG. 7 instead of the warninglamp 31 at the railroad crossing as shown in FIG. 6 and to output alight which is superimposed with a signal via this warning lamp 31.Also, in this case, when the light emitted from the warning lamp 31 isreceived by a light receiving unit 21 on the vehicle 20, contents of thesignal are read out by the decoder 22 to be displayed on the displaypanel 24 by the drive circuit 23.

Still another modification shown in FIG. 8 may be a signal lamp 11embedded in a portion of the traffic lane at an intersection or thelike, in which a modulator 13 is connected between a drive circuit 12for driving the signal lamp 11 and the signal lamp 11. Conversely, onthe side of a vehicle 20, there are connected a light receiving unit 21,a decoder 22, a drive circuit 23 and a display panel 24. A lightemitting unit of the signal lamp 11 is comprised, for example, of LEDs.

Therefore, when the vehicle 20 approaches an intersection, the lightreceiving unit 21 installed on the front end of the vehicle receives thelight superimposed with the signal from the signal lamp 11. Then,contents of the signal in the received light are read out by the decoder22 to be displayed on the display panel 24 by the drive circuit 23.Thereby, it is enabled to convey information whether or not thedirection of the lane the vehicle is passing is a priority road, and asto the presence of traffic regulations inhibiting a left-turn orright-turn and the like.

Next, still more another embodiment of the invention will be describedby referring to FIG. 9. This embodiment is the one applied tocommunication between a traffic signal 10 along a railroad track and atrain car 20. Namely, a modulator 13 is connected between a signal lamp11 of the traffic signal 10 installed along the railroad track and asignal drive circuit 12, and in addition, this modulator 13 is connectedto a receiver 14. The receiver 14 which is provided with an antenna 15receives a command signal from a command base station. Conversely, onthe side of the train car 20, there are provided a light receiving unit21, a decoder 22, a drive circuit 23, a display panel 24 and, further, aspeaker 32. A light emitting unit of the signal lamp 11 is comprised of,for example, LEDs.

Thereby, when the train car 20 traveling on the track approaches thetraffic signal 10, the light receiving unit 21 thereon receives a lightfrom the signal lamp 11 of the traffic signal 10, the decoder 22 thereonreads out a signal superimposed on this light, and the drive circuit 23drives the display panel 24 or the speaker 32 to perform displayoperation or voice output operation. By way of example, as the contentsof display to be displayed here, it may be an instruction concerning theoperation schedule of the train car 20. Besides, any other relatedinformation such as an accident or the like may be conveyedsimultaneously.

(2) Embodiment 2 Inter-vehicle Communication Equipment: FIGS. 10 to 16

This preferred embodiment of the invention is directed to aninter-vehicle communication system for carrying out information transferbetween vehicles using light. That is, as shown in FIG. 10, a head lamp35 and/or a tail lamp 36 already provided on a car are utilized. And amodulator 13 is connected to these lamps 35, 36 for superimposing asignal thereon. Further, a light receiving unit 21 for receiving a lightis mounted respectively at a front end and a rear end of a vehicle 20.And these light receiving units 21 are connected to a decoder 22.Further, these lamps 35, 36 preferably use LEDs, xenon lamp or the likeas its light source to ensure a good responsiveness to the modulation bythe modulator 13.

FIG. 11 shows a system configuration of such vehicle communicationequipment described above, in which the decoder 22 is connected to thelight receiving unit 21, and this decoder 22 is also connected to a CPU25. And the CPU 25 is connected to a CPU 16 on the side of themodulator. The modulator 13 is connected between a drive circuit 23 andthe head lamp 35. And the aforementioned CPU 16 is further connected toan operation input unit 26, a display panel 24 and a memory 27.

As described hereinabove, the system for use in the inter-vehiclecommunication is arranged to receive an external signal via the lightreceiving unit 21. Here, the light receiving unit 21 is comprised of aphoto transistor capable of receiving a light in a visible light range.And the contents of the signal decoded by the decoder 22 are sent to theCPU 16 via the CPU 25, then after processing of the data or program,they are stored in the memory 27. Also, it may be arranged for thememory 27 to have a database, through which a sender's information to besearched, and detailed information such as the names of the sender orcorporations and the like are displayed on the display panel 24. It isalso possible for the contents of transmission to be stored as voicedata and reproduced audibly.

FIG. 12 shows a receive operation of the system shown in FIG. 11. TheCPU 25 detects whether or not the decoder 22 has received a data. If thedata is received, the data thereof is loaded in a D-RAM in the CPU 25 toexecute comparison of ID check results. The reason why the comparison ofthe ID check is carried out is because that in a case where unnecessarycommunication data is received, by going through ID check, only suchdata to be truly displayed are ensured to be extracted. And in a casewhere IDs agree, the received data is analyzed, the database on thememory 27 is searched through, then a display or a voice output isgiven. Further, a received record may be written as required in thememory 27.

As described hereinabove, in the communication system according to thisembodiment of the invention, the receiving side verifies permission onthe basis of ID data contained in the received data. In a case where thepermission is verified, the data is allowed to be analyzed, and in acase where the data is in a voice code, a voice data consistent with thevoice code is retrieved from the database such as CD-ROM or the like tobe annunciated in a voice message. In a case where voice data itself isreceived, it is also possible to announce the voice data. In a case ofdisplay data, and if it is character data, it is displayed as they are.In this case of the character display, it may be “Thank you”, “You maygo ahead”, “Turn right”, “I'm stopping” or the like. In this instance,it is also possible simultaneously to display the sender's data searchedfrom an existing database on one's own vehicle.

FIG. 13 shows an operation of information transmission utilizing thehead lamp 35 and/or the tail lamp 36 on the side of the vehicle 20.Here, the CPU 16 determines whether or not a command was transmitted.The determination whether or not the command was transmitted is judgedon the basis of the operation by the driver if the driver carried outinput operation through an operation input unit 26 or not. And in a casethere was a command input, the input data is loaded in the D-RAM of theCPU 16, and in addition, the CPU 16 adds ID data and category datathereto. Subsequently, the data to be transmitted is sent to themodulator 13. The modulator 13 carries out modulation by superimposingthis signal on a drive current from the drive circuit 23. Thereby, onthe basis of the drive current on which the signal is superimposed, thehead lamp 35 is caused to carry out its light emitting operation. By theway, at this instant, the transmission record thereof may be stored inthe memory 27 connected to the CPU 16.

In communication between the vehicles 20, in a case where a plurality ofvehicles send signals simultaneously, it becomes necessary todiscriminate each to each therebetween. Therefore, as shown in FIG. 14,in order to prevent any erroneous operation in this case, it may bearranged such that a plurality of PLLs 37, 38, 39, 40 which are arrangedin parallel and locked at a different frequency from each other areconnected in a preceding stage of the decoder 22 and in a subsequentstage of the light receiving unit 21. The PLL is composed of a phasecomparator, a low pass filter (LPF) and a voltage controlled oscillator(VCO). In order to carry out a synchronous detection, a plurality ofsignals therebetween are discriminated by use of these PLLs, and only apredetermined signal is enabled to be extracted and to be supplied tothe decoder 22. Thereby, the erroneous operation on the side of thereceiver can be prevented even when it receives a plurality of signalsfrom a plurality of vehicles 20 simultaneously.

FIG. 15 shows a modification of the above. Here is shown an example inwhich a single operation enables for plural different signals differentfrom each other to be outputted to a plurality of other vehicles. Forexample, there may occur such an instance when your car (a vehicle 20 inFIG. 15) approaches an intersection, you find an opposite vehicle (avehicle 50 in FIG. 15) waiting to turn to the right, so you halt yourcar vehicle 20, to let the opposite car vehicle 50, go ahead to turn tothe right. In such a case, if a following vehicle (a vehicle 51 in FIG.15) is informed in advance of your intention to halt, a rear-endcollision or a sudden braking by the following vehicle 51 can beavoided.

Therefore, in a case you want to show your intention to permit theopposite vehicle 50 to go ahead to turn to the right, your car, thevehicle 20 shown in the middle of the drawing, in response to yoursingle key operation, transmits a signal permitting the opposite vehicle50 to turn to the right by sending a message “you may go ahead to turnto the right” which is superimposed on the light of the head lamp 35 viaa modulator 13. And at the same time, to the following vehicle 51, asignal of message “I'm stopping” indicating your intention to halt issent as superimposed on the tail lamp 36 via the modulator 13.

FIG. 16 shows such an operation. For example, in a case where the CPU 16shown in FIG. 11 receives a command to be transmitted in response to asingle key operation, it loads first input data for the vehicle in theforward direction, subsequently loads second data to be transmitted tothe vehicle in the backward direction. Then, the CPU 16 attaches ID datato these data, and the first input data is modulated by the modulator 13to be superimposed on a drive current of the head lamp 35. Thereby, thehead lamp 35 emits a modulated light. Then, the CPU 16 supplies thesecond input data to the modulator 13 so that a signal of the seconddata is superimposed on a drive current for driving the tail lamp 36.Therefore the tail lamp 36 generates a modulated light superimposed withinformation to be conveyed to the vehicle in the backward direction.Thereby, it is enabled to supply almost simultaneously a mutuallydifferent data to the vehicle 50 in the forward direction and to thevehicle 51 in the backward direction.

Although the invention has been described in its preferred form with acertain degree of particularity, obviously many changes, variations andcombinations are possible herein. It is therefore to be understood thatany modifications will be practiced otherwise than are specificallydescribed herein without departing from the scope of the presentinvention. For example, the present invention can be utilized forcommunication between any stationary type light emitting apparatus otherthan those specified in the above and a vehicle. Alternatively, theinvention may be applied for carrying out information transfer betweenvehicles using any other light emitting apparatus other than thoseparticularly specified in the above. Further, in place of the displaypanel for displaying information, it may be arranged to annunciate theinformation in voice using a speaker as well.

Further, according to the present invention, because it is arranged tosuperimpose a modulated light to emission from the light emittingapparatus such as the signal lamp, the warning lamp, the head lamp ofthe vehicle or the like, and to receive the modulated light, influenceby an external light is anticipated. Therefore, it is effective to use apolarizing filter, a band pass filter or the like which is capable ofextracting the wavelength of an output light from-the light emittingapparatus. Alternatively, such a modification may be considered as wellthat uses a shade to shadow a solar light or in which its lightreceiving unit is installed in a recess of the vehicle body.

According to one aspect of the present invention, it is comprised of: alight emitting apparatus installed stationarily; a modulator forsuperimposing a predetermined signal on the light emitted from the lightemitting equipment; a light receiving apparatus installed on the side ofa vehicle for receiving the light which was emitted from the lightemitting apparatus and superimposed with the signal; a decoder forreading out the signal superimposed on the light received by the lightreceiving apparatus; and output means for outputting the signal read outby the decoder.

Therefore, according to such vehicle communication equipment, it becomespossible to transfer information by establishing communication betweenthe light emitting equipment and the vehicle, by utilizing thestationarily installed light emitting apparatus as it is withoutimpairing its function.

Further, the present invention is comprised of: a light emittingapparatus installed on a vehicle for emitting light outwardly; amodulator for superimposing a predetermined signal on the light emittedfrom the light emitting apparatus; a light receiving apparatus mountedon the vehicle for receiving the light which is emitted from a lightemitting apparatus of another vehicle and is superimposed with thesignal; a decoder for reading out the signal superimposed on the lightreceived by the light receiving apparatus; and output means foroutputting the signal read out by the decoder.

Therefore, according to such a vehicle, it becomes possible to carry outcommunication between different vehicles by utilizing existing lightemitting apparatus of respective vehicles for emitting the lightoutwardly as they are without impairing their functions. Therefore, itbecomes possible to provide a vehicle equipped with a communicationsystem that is not only capable of simplifying the construction and isalso advantageous in cost, without the need of installing any additionallight emitting apparatus.

Further, the present invention is comprised of: a light emittingapparatus which is installed stationarily; and a modulator forsuperimposing a predetermined signal on a light to be emitted from thelight emitting apparatus, wherein communication is enabled by emitting alight modulated by the modulator to an external vehicle.

Therefore, according to such vehicle communication equipment, it becomespossible to transfer information by transmitting the signal from thestationary equipment to the vehicle utilizing the light emittingapparatus installed stationarily.

Further, the present invention is comprised of: a light receivingapparatus for receiving a light which is superimposed with apredetermined signal; a decoder for reading out the signal superimposedon the light received by the light receiving apparatus; and notifyingmeans for notifying information based on the signal read out by thedecoder.

Therefore, according to such vehicle communication equipment, it becomespossible to transfer information based on the signal to the vehicle bythe steps of reading out the signal superimposed on the light receivedby the light receiving apparatus by the decoder, and by notifying thedecoded signal by the notifying means.

1. A vehicle communication system, comprising: a light emittingapparatus installed stationarily and configured to emit a visible lightto communicate with an operator of a vehicle; a modulator configured tomodulate the light emitted from said light emitting apparatus bysuperimposing a predetermined signal thereon; a light receivingapparatus installed on a vehicle side and configured to receive aplurality of lights emitted from light emitting apparatuses of othervehicles and superimposed with signals; a plurality of phase-lockedloops arranged in parallel and each locked at a different frequency suchthat the plurality of phase-locked loops discriminate between aplurality of the signals which are simultaneously received from theother vehicles; a decoder configured to read out the signalssuperimposed on the lights received by said light receiving apparatus; acomparison unit configured to compare an identification of the signalswith a predetermined identification such that only data with permissionis extracted; and notifying means for notifying information based on asignal which is read out by said decoder.
 2. The vehicle communicationsystem as claimed in claim 1, wherein said light emitting apparatus is asignal lamp of a traffic signal.
 3. The vehicle communication system asclaimed in claim 1, wherein said light emitting apparatus is a streetlighting lamp.
 4. The vehicle communication system as claimed in claim1, wherein said light emitting apparatus is a warning lamp at a railroadcrossing.
 5. The vehicle communication system as claimed in claim 1,wherein said light emitting apparatus is an embed type signal lampembedded in a vehicle lane.
 6. The vehicle communication system asclaimed in claim 1, wherein said light emitting apparatus is a signallamp of a traffic signal installed along a railroad track.
 7. Thevehicle communication system as claimed in claim 1, wherein said decoderis configured to demodulate a drive current of said light emittingapparatus by superimposing a coded pulse thereon.
 8. A vehicle,comprising: a light emitting apparatus configured to emit a visiblelight outwardly to assist an operator of the vehicle; a modulatorconfigured to superimpose a predetermined signal on the light emittedfrom said light emitting apparatus; a light receiving apparatusconfigured to receive a plurality of lights emitted from light emittingapparatuses of other vehicles and superimposed with signals; a pluralityof phase-locked loops arranged in parallel and each locked at adifferent frequency such that the plurality of phase-locked loopsdiscriminate between a plurality of the signals which are simultaneouslyreceived from the other vehicles; a decoder configured to read thesignals superimposed on the lights received by said light receivingapparatus; a comparison unit configured to compare an identification ofthe signals with a predetermined identification such that only data withpermission is extracted; and output means for outputting a signal readout by said decoder.
 9. The vehicle as claimed in claim 8, wherein saidlight emitting apparatus is a head lamp.
 10. The vehicle as claimed inclaim 8, wherein said light emitting apparatus is a tail lamp.
 11. Thevehicle as claimed in claim 8, wherein said light emitting apparatus isa brake lamp.
 12. The vehicle as claimed in claim 8, wherein said lightemitting apparatus is a turn indicator lamp.
 13. The vehicle as claimedin claim 8, wherein said light emitting apparatus is installed on thevehicle to cast illumination lights or warning lights to externaldirections.
 14. The vehicle as claimed in claim 8, further comprising:discrimination means for discriminating a type of a signal received bysaid decoder and carrying out a signal processing in dependence on thetype thereof.
 15. The vehicle as claimed in claim 14, wherein saiddiscrimination means discriminates the type of signal depending on acategory signal attached to the signal.
 16. The vehicle as claimed inclaim 8, further comprising: key operation means, wherein, in responseto a single operation of the key operation means, a different signal issuperimposed on a respective light shed from a plurality of lightemitting apparatuses installed in said vehicle and the light is emittedfrom each of the light emitting apparatuses.
 17. The vehicle as claimedin claim 8, further comprising: an input unit configured to allow anoperator of the vehicle to input a command to be superimposed by themodulator on the light emitted from the light emitting apparatus.